The present invention relates to a lifting frame assembly used with a hoist or crane for holding elongated beams, trusses and the like, which has a pair of spaced apart lifting frames mounted onto a spreader bar. The lifting frames have lift slides that support the beam and provide a spring load on the beam to be lifted for a selected amount of vertical travel of the spreader bar. The load lift slides also remain engaged with the beam being lifted under the spring load for a selected amount of lowering movement of the lift frame assemblies after the beam is supported on an object.
A problem arises in the construction industry when placing long trusses or beams (called beams for convenience in this specification), into position, in particular, in that the rigging is generally controlled by a crane operator in a cab some distance away from the actual placement. It is possible for a lifted load to unexpectedly hang-up on the surrounding structure before it is secured in its final position. This condition is difficult for the hoist operator to sense. If the crane continues to lower the frame, the lifting hardware will likely prematurely dis-engage from the load. If the now unsecured load dislodges from the surrounding structure, the load falls out of control. This can result in damage to the structure being built, and hazards to workers.
In the prior art there have been springloaded lifts of various designs, but generally the holders and rigging are fairly complex and do not provide for a direct, limited amount of spring load needed for ensuring proper operation.